1. Technical Field
The present invention relates to a manufacturing method of a backlight unit, and to a backlight unit, an electro-optic device, and an electronic apparatus.
2. Related Art
Conventionally, in a liquid crystal display device as an electro-optic device, there has been a light collecting method in which an optical sheet having a plurality of elliptical shaped microlenses is arranged in a backlight unit for liquid crystal display built in the liquid crystal display device so that light from a light source for illumination of the backlight unit is collected effectively to a liquid crystal element (pixel). Moreover, there has been reported many methods of forming a microlens by use of a droplet discharging method (for example, a first example of related art).
As disclosed in a second example of related art, for example, there has been a backlight unit of an edge-lighting type (side-lighting type) which is constructed such that a liner-shaped lamp as a light source is arranged along the side face of a light-guiding plate. Moreover, bas been proposed a method in which a plurality of elliptical shaped microlenses having a long axis and a short axis are formed on a sheet of a synthetic resin and the like by use of molds etc.
JP-A-2004-157430 is a first example of related art.
JP-A-2004-309801 is a second example of related art.
In these methods, however, the number of the liner-shaped lamps capable of being mounted is limited. Therefore, the brightness of a display screen cannot be secured in a case of a large display screen. Moreover, it is difficult to manufacture a large-sized display screen due to a problem of mass of the light-guiding plate. On the other hand, in a direct-lighting type backlight unit where the liner-shaped lamp is arranged directly under the display screen, the number of the liner-shaped lamps is increased depending on the display size. Therefore, there has been no problem in the brightness but may have been problem in a brightness ununiformity due to a brightness difference of the liner-shaped lamp itself and a brightness ununiformity between a portion directly under which the liner-shaped lamp exits and a portion directly under which no liner-shaped lamp exits. In addition, if the liner-shaped lamp is spaced away from the face of the display screen surface, the brightness ununiformity is improved, but the brightness of the display screen is deteriorated, and thereby the thickness of the backlight unit is difficult to be reduced. The number of the liner-shaped lamps can be increased depending on the display size in order to make the display brighter. However, the increase in the number of the lamps may cause the problems such as the heat generation, cost, and others.